In recent years, advances in technology, as well as ever-evolving tastes in style, have led to substantial changes in the design of automobiles. One of the changes involves the complexity of the electrical and drive systems within automobiles, particularly alternative fuel vehicles, such as hybrid, battery electric, and fuel cell vehicles. Such alternative fuel vehicles typically use one or more electric motors, perhaps in combination with another actuator, to drive the wheels.
Such vehicles typically include a vehicle propulsion system having multiple components that contribute to the propulsion of the vehicle. These components can be further grouped into subsystems, such as the drivetrain, the internal combustion engine, and the hybrid electric drive system. The electric drive system typically includes multiple components including sensors, energy storage, electronic inverters, electric motors, and a control system. To ensure the operating integrity of the electric drive system, a multi-layer monitoring system may be used to ensure that the output of the electric drive (torque, speed, etc.) is as requested, or possibly in the case of a fault situation, as delivered.
A commonly employed first layer monitoring system performs diagnostics on all sensor inputs. Such low level diagnostics may include, but are not limited to, checking whether a sensor is able to communicate or checking to see if a sensor reading is in its expected or allowable operating range. Such sensors may include current sensors, voltage sensors, position sensors, speed sensors, temperature sensors, physical and/or virtual software replacements, and the like.
A second layer monitoring system may perform monitoring on the control system to ensure that it is producing outputs as intended. Such a second layer monitoring system will typically monitor the entire control system from input to output or by monitoring the individual components of the control system separately to determine the integrity of the overall control system. For example, a second layer monitoring system can be used to verify that the correct outputs are produced for the given inputs in order to detect errors in the computational processors, memory, and data storage. A conventional method for checking the duty cycles is to essentially perform an entire redundant calculation. However, such a calculation demands considerable processing power and memory.
Accordingly, it is desirable to provide a method and system for performing second layer monitoring of values for electrical systems of vehicles. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent description taken in conjunction with the accompanying drawings and the foregoing technical field and background.